<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>

<body>
    <script>
        var xhr = new XMLHttpRequest()
        xhr.timeout = 30
        xhr.ontimeout = function () {
            alert('超时了')
        }
        xhr.open('get', 'http://www.liulongbin.top:3006/api/getbooks')
        xhr.send();
        xhr.onreadystatechange = function () {
            if (xhr.readyState == 4 && xhr.status == 200) {
                console.log(xhr.responseText);
            }
        }
    </script>
</body>

</html>